Prognostic Value of Diagnostic Prostate Biopsy Percent Carcinoma Volume (PCV) and Percent Positive Cores (PPC) on Treatment Outcomes Following Radiation Therapy (RT): A Retrospective Analysis of 1731 Patients

Purpose/Objective(s): Evaluate PSA dynamics after Pd103 seeds implant brachytherapy (SIB) in prostate cancer patients and assess the relationship of PSA bounce (PSAB) and biochemical recurrence (BR) with postimplant dosimetry (PID). Materials/Methods: One hundred one consecutive prostate cancer patients, age 71 7 yr, Stage T1-2, PSA 6.11 2.84ng/ml (0.7 to 18.7 ng/ml) and prostate volume of 36 10 cc (13 to 56cc), were treated with nomogram based SIB. PSA tests were performed at 1, 3, 6, 12, 18 months and then annually. Time, amplitude and duration of PSAB >0.1 ng/ml were analyzed. Phoenix and ASTRO definitions for BR were utilized. BR was considered actionable after meeting definitions and 2 subsequent PSA rises. Subset analysis of PSA dynamics was performed for PSAB and suspected BR cohorts. PID was done about 4 weeks after implantation. Correlation analysis of PSA patterns and D90 was performed for the whole group, PSAB and BR cohorts. Results: With average follow-up of 52 months (8 to 102 range) BR free survival (BRFS) was 95.0%. In concert with other reports, post-SIB PSA change was slow and inconsistent. 42.6% of patients reached lowest PSA level at 1yr, 19.8% at 2yr, 15.8% at 3yr, 13.9% at 4yr, and 7.9%> 4yr. 55.5% of patients reached nadir of 0.1ng/ml, 10.89% at 0.2ng/ml, 12.9% at 0.2-0.5ng/ml, 8.9% at 0.5-1.0ng/ml, and 11.9% > 1.0ng/ml. 43.6% of patients had PSAB from 6 months to greater than 5 year duration. PSAB exceeded 2.0ng/ml in 15.8% of patients and 4.0ng/ml in 7.9%. The return to nadir after PSAB took 1 year for 9.1%, 2yr for 13.6%, 3yr for 13.6%, 4yr for 6.8%, and 5yr for 2.3% of patients, with the remaining 54.5% having declining PSA but not reaching nadir. There was no statistically significant correlation between D90 and time to PSA nadir in the whole study population (P>0.05), PSAB or BR cohort (P>0.05). No statistically significant correlation was found between D90 and average PSA in the first 6 and 12 months after SIB, or 6 months decrease from pre-SIB value (P>0.05). 7 patients had suspected BR: 4 meeting Phoenix definition, 2 with multiple consecutive PSA rises less than 2.0ng/ml combined, and 1 with initial post-seeds PSA of 3.8 with a subsequent rise to 5.3 at 1-year follow-up. 4 of those patients for different reasons did not receive hormonal therapy. 2 of them were reclassified as PSAB due to spontaneous decrease of PSA at 2 and 8 year follow-up. Thus, only 5 patients remained in BF group. All of them had dosimetry meeting quality standards (D90 Z 109 12%, range 95.2-132%, V100 Z 88.2-98.8%, no cold spots). Conclusions: Excellent BRFS (95%) after seeds implant is associated with frequent (43.6%), prolonged (0.5 to 6 years) and high amplitude (up to 5.9ng/ml) PSAB, which may lead to misdiagnosis of BR and unnecessary treatment. Consensus on how to handle capricious PSA behavior is warranted. Author Disclosure: B.G. Naydich: None. T. Huisman: None. R. Chiaramonte: None. B. Zorn: None. Y. Feng: None. P. Hopko: None. N. Arora: None. S. Parikh: None. K. Settle: None.